Asthma is common. Around 10 percent of Americans have the condition, with hundreds of millions more asthmatics worldwide. Though the ubiquity of asthma may be concerning in and of itself, it’s a subset of people with the condition who bear the brunt of the costs. About a tenth of cases are severe asthma, a condition defined by the ineffectiveness of a combination of conventional treatments. Of the 13 million school days and 11 million workdays missed due to asthma, an outsized proportion stems from the worst cases.
“The burden is carried by this ten percent who we describe as having severe asthma,” says Dr. Victor Ortega, a pulmonary disease specialist and a genetic epidemiologist at the Mayo Clinic.
One way to think of asthma is that it’s defined by its treatment. It’s not simply airway inflammation, but bouts of it severe enough to call for medication—most typically an inhaled combination of steroids and bronchodilators; the former mitigates inflammation while the latter relaxes airway muscles to offer relief from strained breathing. In severe asthma cases, the effects of those drugs are limited. Think of “people on multiple inhalers and medicines who are still going to the hospital,” says Dr. Ortega. “We have to put them on systemic (CK) steroids that have terrible side effects: diabetes, osteoporosis, obesity. These people have to live with it.”
Yet while millions of Americans experience severe asthma, they’re a small minority of total cases. Their small proportion is a testament to the general efficacy of asthma treatment. It also means much energy in advancing treatment has been free to focus on the most difficult cases. The results are emerging. “The more exciting recent advancements are targeting those on all the inhalers,” says Dr. Ortega. He adds that “with current advances, I have the least amount of people going to emergency rooms.”
So, what actually changed? Steroids have long been used to treat asthma with debilitating side effects accepted as a cost of their efficiency. Generally, they can be akin to “throwing a grenade into the body,” says Dr. Ortega.
But advances in their precision over recent years have chipped away at the issue of side effects. “There has been a burst of therapies in the last 10 years targeting different inflammatory pathways,” says Dr. Dr. Linda Rogers, a professor of medicine and clinical director of the Adult Asthma Program at the Mount Sinai National Jewish Health Respiratory Institute. “Those have really been a breakthrough because they’ve been able to help people whose symptoms had not been controlled—even in high doses.” Until recently, more general steroids had to be used at higher frequencies and amounts, causing collateral side effects in users.
Another treatment option which has transformed prospects for severe cases in just the last few years is biologics. These therapies, typically administered intravenously in a doctor’s office, target microscopic targets like allergy antibodies or molecules that cause airway inflammation.
Advances in other fields, like pharmacogenetics, which examines how someone’s genes influence their response to medications, are also having a positive effect on treating asthma. By analyzing a patient’s genetics, Dr. Ortega says healthcare providers could narrow down which treatments might be most effective. Experts’ understanding of the full picture is still limited, but its potential seems mighty. “I have meetings everyday about discovering new genes,” he says.
There are hundreds of gene responses to asthma and its treatments to understand, but eventually Dr. Ortega says doctors might be able to create genetic risk profiles for someone’s vulnerability to asthma. “We hope to get there,” he says.